Image performance was assessed using observations of stars in the open cluster NGC 7790 for which the USNO has accurate astrometry and previous IR photometry to assess the photometric performance of the ALADDIN array. The night was clear and photometric, with 1.2-arcsec seeing reported at WIYN during the night. Typical best images at the 2.1-meter with MOSAIC were 0.8-arcsec FHWM (see below).
There is a separate page with pretty pictures taken during the run.
KPNO 2.1-meter (f/7.8 secondary):
Future calculations with a more complex model should allow measurement of higher-order distortions if present.
NOTE: The MDM 2.4-meter plate scale will be measured during the upcoming October run.
The fundamental limitation on image quality was the failure of the primary mirror support for the 2.1-meter mirror between the J and K frames. The airbags apparently deflated, causing the mirror to set down on its hard points. This results in trefoil shaped image seen in the K-band frame (where we should get our best atmospheric seeing).
Left: J-band image of a star in NGC 7790; Right: K-band image.
Images are single 10- and 5-second integrations, respectively.
Seeing at J and K was 0.8-arcsec FWHM and 0.9-arcsec FHWM, respectively. The latter larger due to problems with primary mirror support. Below are radial profiles of the star images above: